Shell Western E&P Inc. has been operating the Denver Unit CO2 flood, the world's largest CO2 enhanced oil recovery project, since 1983. The unit is in the Wasson Field in Gaines and Yoakum Counties in West Texas. While operating the flood, SWEPI has developed successful technology and operating methods for carbon dioxide flooding.
The paper is structured in three parts: 1) physical properties of CO2, 2) physical effects of CO2, and 3) relative economic considerations associated with CO2. Operational considerations associated with each topic are identified and SWEPI's resulting modifications in operating policy are discussed. Some of the topics included in the paper are equipment and materials, artificial lift, well control, wellbore impairment, injection surveillance, and operations in a populated area. Discussions also include issues where our operating experience has varied significantly from our- original expectations. These include the lower than expected corrosion rate of materials, and the higher than expected number of wells that flow naturally.
This overview will be of interest to companies who are either operating- or preparing to implement CO2 floods. It will also interest service companies who may have- or wish to develop products to service CO2 operations.